1. Field of the Invention
The present invention relates to antigas/antiflatulent oral solid pharmaceutical dosage forms comprising an admixture of simethicone and anhydrous tribasic or dibasic calcium phosphate, free flowing granular compositions for preparing such dosage forms and methods for their production.
2. Background
Simethicone is a mixture of fully methylated linear siloxane polymers containing repeating units of polydimethylsiloxane stabilized with trimethylsiloxy end-blocking units, and silicon dioxide. Simethicone contains 90.5-99% of polydimethylsiloxane and 4-7% silicon dioxide. The polydimethylsiloxanes present in simethicone are practically inert polymers having a molecular weight of 14,000-21,000. The mixture is a gray, translucent, viscous fluid which is insoluble in water.
When administered orally, simethicone is used as an adjunct in the symptomatic treatment of flatulence, functional gastric bloating, and postoperative gas pains. The clinical use of simethicone is based on its antifoam properties. Silicone antifoams spread on the surface of aqueous liquids, forming a film of low surface tension and thus causing the collapse of foam bubbles. Thus for self medication in over-the-counter preparations, simethicone is used as an antiflatulent to relieve symptoms commonly referred to as gas, including upper GI bloating, pressure, fullness, or stuffed feeling. It is often combined with other gastrointestinal medications, such as antacids, antispasmodics or digestive enzymes and various simethicone formulations are disclosed in the prior art.
Simethicone can be administered orally as a liquid preparation or as solid form for example capsules, chewable or swallowable tablets. The preferred form for ease of administration is a swallowable tablet. The advantage of tablets over liquids is the ease of portability. The advantages of swallowable tablets over chewable tablets include the ease of ingestion and lack of taste. Film coated or gelatin coated tablets are preferred for swallowable tablets.
Historically, in preparing solid simethicone dosage forms, difficulties have been encountered when attempting to incorporate substantial quantities of the liquid simethicone in the solid final blend for tableting. The difficulty has been to achieve sufficient cohesion in the compact for compression, particularly for direct compression tableting, so that the tablet will withstand the rigors of further processing, i.e. film coating, gelatin dipping, printing, packaging and the like. Likewise, difficulties have been encountered in assuring that the viscous liquid simethicone is uniformly distributed throughout the solid formulation and expeditiously dispersed upon administration.
An object of the present invention, therefore, is to provide a composition and process wherein substantial quantities of liquid simethicone can be incorporated into solid tablet formulations for manufacture by a dry blend/direct compression process.
U.S. Pat. No. 4,906,478 discloses a simethicone preparation comprising a powdered combinate of particulate calcium silicate and simethicone. U.S. Pat. No. 5,073,384 discloses simethicone preparations comprising combinates of water soluble agglomerated maltodextrin and simethicone. U.S. Pat. No. 5,458,886 discloses a free-flowing granular composition comprising titanium dioxide having specific particle size and surface area in combination with simethicone. While these methods are of some benefit in achieving a simethicone composition suitable for the dry blend/direct compression manufacturing process, the present invention provides further improvements to accomplish the object of providing a composition which may be easily and inexpensively formulated into potent swallowable or chewable tablets.